I've tested the following: Last snapshot AR71 r14042-b92f54b infos here
Sysupgrade from Luci some minutes later ATH79 successfully installed with the old configuration. Access via SSH only. And tested upgrade from Luci without keep the configuration and restore the configuration from ATH79 successfully. But read the this infos
Hi DirkP,
Is the snapshot version stable for you on the TL-WR740N v4? I was also able to build and install successfully, but it seems to be crashing/rebooting every 4 hours or so. Not sure if it's a shortage of RAM (kernel 5.4 does take up a bit more) or something else, and I haven't yet gotten up to speed on crash logging/forensics to investigate in more detail.